TreeView.AfterCheck Událost

Definice

Obor názvů:

System.Windows.Forms

Sestavení:

System.Windows.Forms.dll

Zdroj:

TreeView.cs

Nastane po zaškrtnutí políčka uzel stromu.

public:
 event System::Windows::Forms::TreeViewEventHandler ^ AfterCheck;

public event System.Windows.Forms.TreeViewEventHandler? AfterCheck;

member this.AfterCheck : System.Windows.Forms.TreeViewEventHandler 

Public Custom Event AfterCheck As TreeViewEventHandler 

Event Type

TreeViewEventHandler

Příklady

Následující příklad kódu aktualizuje všechny uzly podřízeného stromu uživatele TreeNode , když uživatel změní stav kontroly. Tento kód vyžaduje, abyste měli s FormTreeViewTreeNode objekty v jeho TreeNodeCollection. Měly TreeNodeCollection by obsahovat uzly stromu s podřízenými uzly.

// Updates all child tree nodes recursively.
void CheckAllChildNodes( TreeNode^ treeNode, bool nodeChecked )
{
   IEnumerator^ myEnum = treeNode->Nodes->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      TreeNode^ node = safe_cast<TreeNode^>(myEnum->Current);
      node->Checked = nodeChecked;
      if ( node->Nodes->Count > 0 )
      {
         
         // If the current node has child nodes, call the CheckAllChildsNodes method recursively.
         this->CheckAllChildNodes( node, nodeChecked );
      }
   }
}

// NOTE   This code can be added to the BeforeCheck event handler instead of the AfterCheck event.
// After a tree node's Checked property is changed, all its child nodes are updated to the same value.
void node_AfterCheck( Object^ /*sender*/, TreeViewEventArgs^ e )
{
   // The code only executes if the user caused the checked state to change.
   if ( e->Action != TreeViewAction::Unknown )
   {
      if ( e->Node->Nodes->Count > 0 )
      {
         /* Calls the CheckAllChildNodes method, passing in the current
             Checked value of the TreeNode whose checked state changed. */
         this->CheckAllChildNodes( e->Node, e->Node->Checked );
      }
   }
}

// Updates all child tree nodes recursively.
private void CheckAllChildNodes(TreeNode treeNode, bool nodeChecked)
{
   foreach(TreeNode node in treeNode.Nodes)
   {
      node.Checked = nodeChecked;
      if(node.Nodes.Count > 0)
      {
         // If the current node has child nodes, call the CheckAllChildsNodes method recursively.
         this.CheckAllChildNodes(node, nodeChecked);
      }
   }
}

// NOTE   This code can be added to the BeforeCheck event handler instead of the AfterCheck event.
// After a tree node's Checked property is changed, all its child nodes are updated to the same value.
private void node_AfterCheck(object sender, TreeViewEventArgs e)
{
   // The code only executes if the user caused the checked state to change.
   if(e.Action != TreeViewAction.Unknown)
   {
      if(e.Node.Nodes.Count > 0)
      {
         /* Calls the CheckAllChildNodes method, passing in the current 
         Checked value of the TreeNode whose checked state changed. */
         this.CheckAllChildNodes(e.Node, e.Node.Checked);
      }
   }
}

' Updates all child tree nodes recursively.
Private Sub CheckAllChildNodes(treeNode As TreeNode, nodeChecked As Boolean)
   Dim node As TreeNode
   For Each node In  treeNode.Nodes 
      node.Checked = nodeChecked
      If node.Nodes.Count > 0 Then
         ' If the current node has child nodes, call the CheckAllChildsNodes method recursively.
         Me.CheckAllChildNodes(node, nodeChecked)
      End If
   Next node
End Sub
      
' NOTE   This code can be added to the BeforeCheck event handler instead of the AfterCheck event.
' After a tree node's Checked property is changed, all its child nodes are updated to the same value.
Private Sub node_AfterCheck(sender As Object, e As TreeViewEventArgs) Handles treeView1.AfterCheck
   ' The code only executes if the user caused the checked state to change.
   If e.Action <> TreeViewAction.Unknown Then 
      If e.Node.Nodes.Count > 0 Then
         ' Calls the CheckAllChildNodes method, passing in the current 
         ' Checked value of the TreeNode whose checked state changed. 
         Me.CheckAllChildNodes(e.Node, e.Node.Checked)
      End If
   End If
End Sub

Poznámky

TreeNode.Checked Nastavení vlastnosti z obslužné BeforeCheck rutiny události nebo AfterCheck události způsobí, že událost bude vyvolána vícekrát a může způsobit neočekávané chování. Pokud chcete zabránit vícenásobnému vyvolání události, přidejte do obslužné rutiny události logiku, která spouští pouze rekurzivní kód, pokud Action vlastnost objektu TreeViewEventArgs není nastavena na TreeViewAction.Unknown.

Další informace o zpracování událostí naleznete v tématu Zpracování a vyvolávání událostí.

Viz také

• CheckBoxes
• OnAfterCheck(TreeViewEventArgs)
• BeforeCheck
• OnBeforeCheck(TreeViewCancelEventArgs)